Conventionally, information processing systems use a technology of a virtual private network (hereinafter, referred to as “VPN). Plural points connected to a communication line such as Internet could communicate with each other as if they are connected to each other through an exclusive line, by using the technology. This configuration is disclosed in Charlie Scott's Document (“Virtual Private Networks, Second Edition” written by Charlie Scott, Paul Wolfe, and Mike Erwin, O'REILLY, December of 1998, P1˜9 and P11 to 22).
However, a complex setup for a device serving as a connection point such as a router is required to connect plural local area networks. A user should make such a setup. Therefore, if the user cannot set up a network well, it is not easy to make a communication between plural points.